Questions and Answers about
Spraying for Adult Mosquitoes

How are adult mosquitoes controlled?

Mosquito control agencies use truck-mounted fogging units to apply
insecticides as an ultra-low-volume (ULV) spray. ULV spray units dispense very
fine aerosol droplets (fog) that stay aloft and kill mosquitoes on contact. The
amount of insecticide sprayed by ULV units is small compared to the area
treated, usually about 3 to 5 ounces per acre, which minimizes exposure and
risks
to people and the environment. Some communities have
thermal foggers that use an oil carrier that is heated to disperse the
pesticide in a dense smoke-like fog.

What agency conducts mosquito control in my town?

With a few exceptions, where mosquito control is conducted, it is locally
funded and carried out by village or city governments. Some communities are
part of a local government agency called a mosquito abatement district that
receives local property taxes to conduct mosquito control operations.

Why is the local government fogging for mosquitoes in my
community?

Some communities decide to fog because of the nuisance caused by hoards of
biting mosquitoes. In some situations, officials may decide to fog because
testing of mosquitoes and wild birds may have shown that mosquito-borne West
Nile virus or St. Louis encephalitis virus is present in the community. Contact
your local government or mosquito control agency to determine why that agency
has decided to fog for mosquitoes.

Why do they fog for mosquitoes when I am out taking my evening walk?

The best time to kill adult mosquitoes by fogging is at dusk, when they are
most active and looking for food (mosquitoes feed on human or animal blood).
The aerosol fog primarily targets flying mosquitoes, which is why the timing of
the spray is critical.

Will local officials notify me before fogging?

There is no law in Illinois that requires local governments to notify
citizens before fogging for mosquitoes. However, many mosquito control agencies
will notify individuals who request notification before fogging begins.
Contact your local government office or mosquito control agency if you wish to
be notified.

What insecticides are used to fog for mosquitoes?

The most commonly used products are synthetic pyrethroid insecticides (such
as Scourge ® and Anvil ®), pyrethrins and
malathion. All insecticides used for mosquito control in Illinois must be
registered with the U.S. Environmental Protection Agency (USEPA) and the
Illinois Department of Agriculture (IDA). You can find fact sheets about some
insecticides commonly used to kill mosquitoes on the USEPA web site,
<http://www.epa.gov/opp00001/factsheets/skeeters.htm>.

How long does the fog kill mosquitoes?

During the fogging, flying mosquitoes within the treated area are killed.
Although the local mosquito population is reduced for a few days, fogging does
not prevent mosquitoes from re-entering the area.

If the city has been fogged for mosquitoes, are all mosquitoes in my
area eliminated?

Fogging will kill only part of the mosquitoes in your area for a few days.
Consequently, individuals should always use personal protection when mosquitoes
are present:

Make sure door and window screens fit tightly and all holes are repaired.

Use mosquito netting when sleeping outdoors or in an unscreened structure,
and to protect small babies any time they are outside.

If participating in outdoor activities when mosquitoes are biting, wear
protective clothing (shoes, socks, shirt and long pants). For additional
protection from mosquitoes, use an insect repellent. The more DEET a product
contains, the longer the repellant can protect against mosquito bites. However,
concentrations higher than 50 percent do not increase the length of protection.
For most situations, 10 percent to 25 percent DEET is adequate. Apply
repellents to clothes whenever possible; apply sparingly to exposed skin if
label permits. Consult a physician before using repellents on young children.

Are the insecticides used for fogging safe?

The USEPA reviews and approves insecticides (and other pesticides) and their
labeling to ensure those used to protect public health are applied by methods
that minimize the risk of human exposure and adverse health and environmental
effects. Generally, there is no need to relocate during mosquito control
fogging. The insecticides have been evaluated for this use and have been found
to pose minimal risk to human health and the environment when used according to
label directions. For example, USEPA has estimated the exposure and risks to
both adults and children posed by ULV aerial and ground applications of the
insecticides malathion and naled. For all the scenarios considered, exposures
ranged from 100 to 10,000 times below the amount of pesticide that might pose a
health concern. These estimates assumed several spraying events over a period
of weeks and also assumed that a toddler would ingest some soil and grass in
addition to dermal exposure. Other mosquito control insecticides pose similarly
low risks. Nevertheless, because insecticides are inherently toxic, no
pesticide is absolutely risk free. The likelihood of experiencing adverse
health effects as a result of exposure to any pesticide depends primarily on
the amount of pesticide that a person contacts and the amount of time the
person is in contact with that pesticide. In addition, a person's age, sex,
genetic makeup, lifestyle and/or general health characteristics can affect his
or her likelihood of experiencing adverse health effects as a result of
exposure to insecticides. Although mosquito control insecticides pose low
risks, some people may prefer to minimize or to avoid exposure to these
chemicals. Here are some common sense steps to help reduce possible exposure to
insecticides:

Listen and watch for announcements in the local media about fogging for
mosquitoes and remain indoors during the application in your neighborhood.

If possible, remain inside whenever fogging takes place.

People who suffer from chemical sensitivities or feel fogging could
aggravate a preexisting health condition should consult their doctor or local
health department and take special measures to avoid exposure.

Close windows and doors and turn off your air conditioning (or set it to
circulate indoor air) when fogging is taking place in the immediate area.

Do not let children play near or behind truck-mounted applicators when they
are in use. To ensure the fogging trucks have left the area, keep children
inside during fogging and for about one hour after fogging.

Consult your doctor if you think you are experiencing health effects from
the fogging.

More information about spraying for adult mosquitoes may be found on the
USEPA's Web site:
<http://www.epa.gov/pesticides/citizens/pmcfs.pdf>.

Do I need to wash home-grown fruits and vegetables
after the mosquito fogging?

The amount of insecticide used to fog for adult mosquitoes is much smaller
than that used to spray fruit and vegetable insect pests. However, it is always
a good idea to wash fruits and vegetables before eating them to remove soil and
other contaminants.

What should I do if I have medical
questions about insecticides?

If you suspect that you are reacting to an
insecticide, call your physician or local
poison control center. The Illinois Poison
Center emergency telephone number is 1-800-222-1222;
312-906-6185 (TTY/TDD).

Additional information about the active ingredients in insecticides may be
obtained from the National Pesticide Information Center (NPIC) at
1-800-858-7378 from 8:30 a.m. to 6:30 p.m. (Central time) seven days a week,
excluding holidays; or visit NPIC's Web site at
<http://npic.orst.edu/>.

Will the fogging kill birds or other
large animals?

During the pesticide registration process, USEPA considers the effect of
insecticides on wildlife. If the insecticide is applied according to label
directions, wildlife should not be killed or injured with the exception of
insects similar in size to mosquitoes. If you have any concerns about this
issue after they have sprayed in your area, contact IDA.

Are individuals who do mosquito control required to be
licensed?

Yes, all individuals who use insecticides to control mosquitoes are required
to be licensed by IDA. There are two exceptions: homeowners who fog for
mosquitoes on their own residential property and individuals who use certain
insecticides to treat tires for mosquitoes at tire shops, tire recycling sites
and similar businesses. For information about mosquito control licensing, call
IDA at 217-785-2427.

Can I fog my backyard for mosquitoes?

If you choose to fog your yard for mosquitoes, be sure to use only
insecticides labeled for control of adult mosquitoes. Be sure to follow the
label directions exactly. However, spraying your backyard with an insecticidal
fog or mist is effective only for a short time. If the insecticide label
permits, spraying dense vegetation like that found along the edge of a woods
where mosquitoes rest will last somewhat longer. Mosquitoes will return when
the effect of the spray has ended.

Can I treat a depression that floods in my backyard
for mosquitoes?

If the depression floods for 10 or more days, it can produce mosquitoes.
However, use ONLY insecticides that are labeled for treating water for
mosquitoes. Small impoundments of water can be treated for mosquito larvae with
"Bti," a bacterial insecticide. One product that is available at many
hardware stores for this purpose is doughnut-shaped Bti briquets (Mosquito
Dunks ®). Be sure to follow the insecticide label directions
exactly.

Can communities use other methods to control mosquitoes besides
fogging?

Yes, some communities conduct community-wide mosquito abatement programs.
Whenever possible, the primary effort of such programs should be identification
of mosquito-breeding sites, followed by removal or treatment of these sites
with an insecticide used for control of mosquito larvae (the immature form of a
mosquito). Also, homeowners should remove old tires and other unused
water-holding containers, change the water in birdbaths, and drain wading pools
weekly. Insect light electrocutors ("bug zappers") or sound devices
do little to reduce biting mosquitoes in an area. Installing bird or bat houses
to attract these insect-eating animals has been suggested as a method of
mosquito control. However, there is little scientific evidence that this
significantly reduces the mosquito population around homes. More information
about mosquito control methods may be found at
<http://www.epa.gov/pesticides/citizens/mosquitojoint.htm>.